When Lightroom starts out closed, and I do my work in PM, and use EDIT to send the photos to LR, everything works fine. But if LR is already open, I get what's shown in the attached file.

The easy fix is to close LR before sending over the images.Is there a better way?

Lightroom doesn't work well as an "Editor" in that it responds differently to images being sent to it when running versus not yet running. Many users have found drag and drop to be more consistent and effective. In Photo Mechanic select the photos you want to edit and drag and drop them onto Lr. It should consistently result in the import module handling the images.